Yes, I used it last year in my hard ciders. I don't know if it made any difference, or not. I should have done a split batch, half with the MLF enzymes, and half without. I probably won't use it in the future. But, if I do, I would split a batch just to see what, if any, difference there might be.

The question is whether you need MLF culture
If the cider finishes tasting pretty good, except for an intense sour apple gumball finish (high malic acid) which does not fade in a couple months due to natural MLF (or you do not want to wait a couple months), then yes, adding culture is helpful. Otherwise you dont need it.

The question is whether you need MLF culture
If the cider finishes tasting pretty good, except for an intense sour apple gumball finish (high malic acid) which does not fade in a couple months due to natural MLF (or you do not want to wait a couple months), then yes, adding culture is helpful. Otherwise you dont need it.

One of the things I like about cider is that "bite" you get at the finish. As CvilleKevin says, if it's an unpleasant finish, you may have to do MLF if it doesn't happen spontaneously or if you need to do it for flavor reasons.

I personally like ciders that have NOT undergone MLF because they taste more cider-like and not as wine-like.

__________________Broken Leg BreweryGiving beer a leg to stand on since 2006

How long should it take for the MLF to kick off after inoculation? Is there a usual lag? It has been 3 days and I'm not seeing bubbles.

MLF activity is less noticable compared to regular fermentation. If you are using a carboy, look for tiny little bubbles rising from within. You may not see any or very little airlock activity during MLF. Did you use a MLF nutrient addition prior to adding the culture? This aids in MLF potential and activity.